Electric water heating container with water level responsive heater control means



JOct. 8, 1968 YONG WON KIM ELECTRIC WATER HEATING CONTAINER WITH WATER LEVEL RESPONSIVE HEATER CONTROL MEANS Filed Oct. 28, 1965 ATTORNEY United States Patent ELECTRIC WATER HEATING CONTAINER 'WITH WATER LEVEL RESPONSIVE HEATER CON- TROL MEANS 1 Yong Won Kim, N0. 6, Z-Chome, Tukagawashirakawa-cho, Koto-ku, Tokyo, Japan Filed Oct. 28, 1965, Ser. No. 505,552 6 Claims. (Cl. 219-333) ABSTRACT OF THE DISCLOSURE An electric water heating container having means to deenergize the heating element when the water level falls below a safe level in order to prevent dry operation and consequent damage to the container. The container includes a heating element wound on a bobbin supported on the bottom interior thereof. A float housing a mercury switch is secured by means of a universal joint to a stand attached to the upper surface of the bobbin. Lead'wires spirally wound about the universal joint connect the switch to the heating element. The universal joint permits the float to incline in .any direction to deenergize the heating element.

The present invention relates to improvements in an electric water heater with idle burning preventing device.

It is one object of the present invention to make the operation of a mercury switch more precise and ideal with lowering of the level of the Water enclosed within a case and to make it possible to keep the water at a constant temperature.

- It is another object of the present invention to provide an electric water heater with idle burning preventing device which is extremely easy and safe to handle and is best suited especially for use in a hospital as a fixture.

It is another object of the present invention to provide a water heater comprising a water container, a bobbin at the bottom of the interior of the water container, electric heating wires wound on the bobbin, a stationary stand releasably fixed on the upper surface of the bobbin, a universal joint, a float operatively connected to the center of the upper part of the stationary stand free of inclination through the universal joint, a mercury switch housed in the float and lead wires extending from the mercury switch and through the bottom of the float and wound spirally on the universal joint and connected in series to the electric heating wires.

In accordance with the present invention there is provided a water heater having therein a universally movable float housing a mercury switch, which switch turns the unit off automatically when the water level in the water heater becomes too low.

With the above and other objects in view which will become apparent in the following detailed description, the present invention will 'be clearly understood in connection with the accompanying drawing, in which:

FIGURE 1 is an elevational view, partly in section, of an electric water heater in accordance with the present invention;

FIG. 2 is a front elevation of the water heater;

FIG. 3 is a longitudinal section of the mercury switch;

FIG. 4 is a perspective view of a bobbin;

FIG. 5 is a perspective view of a stationary stand; and

FIG. 6 is a schematic view of the electrical connections.

Referring now to the drawings, and more particularly to FIGS. 1 and 3, .an electric water heater in accordance with the invention has a case 5 housing a float 9 accommodating therein a mercury switch A in such a manner that the float 9 can be freely tilted in all directions, universally, in the lower part of the case 5.

3,405,249 Patented Oct. 8, 1968 The electric water heater in accordance with the invention further comprises a bobbin 4 (FIG. 4) fixed at the bottom of the case 5 and having radially protruding leg pieces 1 with a plurality of posts 2 studded thereon and arranged in concentric circles from the center of the bobbin. The posts are coiled with a heating wire wrapped in an insulating material such as heat resistant polyethylene. One end of the heating wire 3 passes through the mercury switch mechanism A and exits from the case 5 together with the other end of the heating wire and is connected in series with a thermostat 7 (FIGS. 1 and 6) which in turn is connected to a power supply via a lead wire 6 (FIG. 6).

Referring now again to the drawings, and more particularly to FIG. 3, the mercury switch mechanism A includes a hollow hemispherical float 9 enclosing a mercury switch 8. The float 9 is provided with a pin 10 at the bottom thereof, and a rotator 11 is rotatably mounted on the pin 10. At the bottom of the rotator 11 is provided a projector 14 which is pivotally connected with a connector 13. The connector 13 is further pivoted with another projector 18 to a rotator .12 rotatably mounted on a stationary stand B. That is, the projectors 14 and 18 of the connector 13 are disposed at right angles to each other. The stationary stand B (FIG. 5) has three legs 15 extending at three sides. The legs 15 are fixed onto the bobbin 4 (FIG. 4) by inserting the same into a plurality of posts 16 studded on the central part of the bobbin 4. Lead wires 17 of the mercury switch 8 may be loosely drawn out directly from the bottom of the float 9, preferably by coiling spirally as illustrated in FIG. 3.

The mercury switch mechanism A (FIG. 3), can freely move in all directions, since the float 9 rotatably connected to the rotator 11 and the stationary stand B rotatably connected to the connector 13 can turn in their respective planes, and the rotator 1.1 which is rotatably connected to the connector 13 can swing in the front and rear directions. The connector 13 is rotatably connected to the lower rotator 12 and can move freely upon shaking to the right and left, and the float 9 can swivel smoothly and universally in all planes of inclination up to 360 degrees around the connector 13 as a center, thereby enabling the switch 8 to effect an on and off operation, depending on the standing position of the float 9.

In this case, it is usually preferable to use such a mercury switch which turns off when inclined at an angle of 45 degrees. Accordingly, when the water level in the case 5 is higher than the bottom surface of the float 9, the float stands erect due to its buoyancy, and the mercury switch 8 is on. When the water level becomes sufiiciently low to cause the float 9 to incline, the mercury switch 8 turns 01f, so that as the water level is lowered, the heating wire 3 is rendered in an open circuit state, thereby perfectly preventing any danger of socalled empty boiling. Further, as the electric water heater in accordance with the present invention is composed of heat-resistant plastics, it is superior in anti-corrosive and insulation properties and is light in weight as compared with metallic materials, and the mass produution thereof is easily attained. By attaching the thermostat 7 on the inner face of the case 5, the water within the case can be maintained at a constant temperature, and the temperature of the water can be regulated as desired. In addition, if by any chance an accidental current should develop, the current is shut off by a safety current fuse, so that the water heater can be very safely used without danger of fire.

Further, as a means for effecting a universal movement of the float 9, it is preferable that the connection between the connector 13 and both rotators 11 and 12 is of the known construction of a universal joint. To simplify the construction in these parts, a coil spring may be attached directly to the bottom of the float 9, or the lead wires of the mercury switch 8 may be merely coiled so that the float 9 can move in an arc to one direction.

While I have disclosed several embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

What I claim is:

1. A water heater with a switch for preventing idle burning, comprising:

a water container,

a bobbin at the bottom of the interior of said water container,

electric heating wires wound on said bobbin,

a stationary stand releasably fixed on the upper surface of said bobbin,

a universal joint,

a float disposed above and operatively connected to the center of the upper part of said stationary stand free of inclination by said universal joint,

a mercury switch housed in said float, and

lead wires extending from said mercury switch through the bottom of said float and wound spirally on said universal joint and connected in series to said electric heating wires.

2. The water heater, as set forth in claim 1, wherein:

said bobbin is fixed at the bottom of said container and comprises a plurality of legs extending in radial directions,

a plurality of posts vertically disposed on the upper surface of said legs, and

said electric heating wires being Wound on said plurality of posts.

3. The water heater, as set forth in claim 2, wherein:

said electric heating wires are sheath wires coated with heat resistant plastic.

4. The water heater, as set forth in claim 1, further comprising:

a plurality of support posts secured to said bobbin,

said stationary stand comprises,

7 a plurality of stand legs, and t p t ,7

said plurality of stand legs are releasably mounted in said plurality of support posts, respectively, on,s aid bobbin. I

5. The water heater, as set forth in claim 1, wherein said float is supported by said universal joint and the latter includes,

a double construction coiled spring formed of said lead wires from said mercury switch and extending through the bottom of said float and adapted for resilient inclination of said float.

6. A water heater comprising:

a water container adapted to hold water therein,

a bobbin fixedly disposed at the bottom of the interior of said water container,

electric heating wires surrounding said bobbin,

a stationary stand mounted on said bobbin,

a universal joint, v

a float disposed above and operatively connected to said stationary stand by said universal joint and floating in suspension in said water container, and

a switch means disposed in said float and operatively connected electrically to said electric heating wires for turning off current through said electric heating wires when said float inclines a predetermined amount due to a low 'level of water.

References Cited UNITED STATES PATENTS ANTHONY BARTIS, Primary Examiner. 

